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You can use something PC File Recovery from www.convar.de and use it to recover your files. Depending on what OS you are using, you'll need to either boot from DOS or something like BartPE from http://www.nu2.nu/pebuilder/ to recover your files.

Have you done this already or are you thinking about it?
If you are trying "freshen up "your system by reinstalling the OS & applications then before you do this back up any important files.
If on the other hand you have somehow deleted the entire drive,(have you formatted or fdisked the drive or maybe changed a partiton in someway) then you are going to need a data recovery program.
For a huge list of tools & their links see herehttp://www.experts-exchange.com/Storage/Q_20778366.html
thanks to crazyone for the list
good luck